1. Field of Invention
The invention relates to apparatus for preventing undesirable rotation of screw bolts or the like provided at their ends with spanner working surfaces, in particular for large screw bolts.
2. Description of Prior Art
Cases arise in which moments which tend to turn the screw bolt act indirectly or directly on a screw bolt, even though this is undesirable. The same applies, in particular, to screw bolts which are designed as gudgeons and are screwed into receiving threads in a base member. If a nut located on the screw bolt is to be unscrewed, it may jam and tend to entrain the screw bolt. Such problems arise, among other things, with large screw bolts of the type used for lid seals for pressure vessels and the like.